A visual denaturation bubble-mediated strand exchange amplification and RGB visual analysis-based assay for quantitative detection of Helicobacter pylori in saliva.

Helicobacter pylori (H. pylori) is a class I carcinogen causing gastric cancer. Almost 50% of people on earth have been infected and it is worse in developing countries. Early diagnosis of H. pylori infection is the most important strategy for preventing the spread and worse consequences. H. pylori can be isolated from human saliva, and the sampling of saliva is easy and convenient. Therefore, we developed a visual denaturation bubble-mediated strand exchange amplification and RGB visual analysis-based assay for quantitative detection of H. pylori in saliva in this study. Under the optimized reaction temperature and time, the SEA reaction could be finished in 30 min with a simple reaction system and low dependency on equipment. The detection results could be qualitatively identified by the naked eye and quantitatively analyzed by a developed RGB visual analysis method. The limit of detection (LOD) of RGB visual analysis was 10.8 CFU/mL. This assay had good specificity and anti-interference capacity. In the artificial contamination test, the recovery rate of our assay was between 99.3% and 111.5%, with RSD values ranging from 1.7% to 3.5%. These indicated our assay also had good reliability in the detection of saliva. We believe this assay showed good potential for better non-invasive diagnosis of H. pylori infection.